Laser-induced thermal transfer processes are well known in applications such as color proofing, electronic circuits, and lithography. Such laser-induced processes include, for example, dye sublimation, dye transfer, melt transfer, and ablative material transfer.
Laser-induced processes use a laserable assemblage comprising (a) a thermally imageable element that contains a thermally imageable layer, the exposed areas of which are transferred, and (b) a receiver element having an image receiving layer that is in contact with the thermally imageable layer. The laserable assemblage is imagewise exposed by a laser, usually an infrared laser, resulting in transfer of exposed areas of the thermally imageable layer from the thermally imageable element to the receiver element. The (imagewise) exposure takes place only in a small, selected region of the laserable assemblage at one time, so that transfer of material from the thermally imageable element to the receiver element can be built up one pixel at a time. Computer control produces transfer with high resolution and at high speed.
The equipment used to image thermally imageable elements is comprised of an imaging laser, and a non-imaging laser, wherein the non-imaging laser has a light detector that is in communication with the imaging laser. Since the imaging and non-imaging lasers have emissions at different wavelengths, problems occur with the proper focus of the imaging laser.
A need exists for a process for adjusting the focus of the imaging laser for imaging a thermally imageable element.